The goal of this program is to examine the extent to which functional relationships between light scattering and corneal structure can be developed. Such relationships enable one to infer structural features from light scattering measurements. We have already shown that the variation of scattering power with wavelength, in the visible spectrum, can be used to characterize the structural arrangement of the stromal collagen fibrils in normal and cold swollen rabbit corneas. In particular, these variations evidence a short ranged ordering of fibrils in normal stromas and the presence of regions void of fibrils in swollen stromas. Structural information is also contained in the changes of light scattering intensity with angle, and methods will be devised for extracting this information from angular light scattering measurements. An instrument is being built to measure light dispersion from extremely small areas of corneal tissue (approximately 5 micron m in diameter at 90 degrees). This feature of the apparatus will give us a unique capability to measure the depth dependence of structure in fresh (unfixed) tissues. The incident beam will be focused to a width of approximately 10 micron m, thus allowing these depth dependent measurements to be made even at small angles. This apparatus will also extend the spectral region available for measurement into the near ultraviolet and near infrared, where theory suggests additional structural information can be obtained. In these studies light scattering measurements will be used to characterize corneas whose physiological conditions have been carefully controlled. Theoretical light scattering techniques will be used to calculate the scattering from the structures depicted in electron micrographs from various depths within the corneas. Comparison with the experimental light scattering data will both test the validity of these structures and determine the extent to which light scattering affords a technique for probing structure.